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CARL AZUZ, HOST, CNN STUDENT NEWS: Welcome to CNN STUDENT NEWS. I`m Carl Azuz. Today show leads off at the latest developments surrounding Monday`s terrorist attack in Boston. Authorities say, they are making significant progress on the case. As of yesterday afternoon, no arrests have been made. Three people were killed and more than 180 others were wounded, at least 100 of those people have been released from local hospitals.

President Obama is scheduled to be in Boston today, he was planning to attend an interfaith service this morning that`s dedicated to victims of Monday`s attack. We now know the identity of all three people who were killed in the bombing. Yesterday, we talked about Martin Richard and Krystle Campbell. The third person is Lingzi Lu. She was a graduate student from China studying math and statistics at Boston University. Authorities are working through all the evidence including fragments that they think were part of the bombs. Tom Foreman has more on the investigation efforts and how technology that`s used for the marathon could help out.

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TOM FOREMAN, CNN CORRESPONDENT: Investigators seem to be focusing on three critical hours near the finish line: one hour before the elite runners came sweeping up Boylston Street, they did one final security sweep, checking for bombs there. Then 17,500 runners or so came up, crossed the finish line, and other 6,000 were on their way when the first bomb went off, about three hours after that security sweep. 12 seconds after that, the second bomb went off, some distance down the road.

So, what are investigators looking for? Let me rotate this around so you can look right down the race course here. They are looking for anybody who saw something in this area that would directly relate to the dropping off of a package, somebody doing something suspicious that would really jump out. That`s what they are asking for. All those photographs, all that video to see if they might find clues to things like this: this photograph has attracted a lot of attention, because you see that package sitting right there? That`s right, near the spot where there was one of the explosions, a lot of people are wondering if that was one of the parcels that may have been dropped off here, that blew up. So, investigators are going to try to find people who can say, yes, I saw someone with a package like that. Yes, I saw this person leave it there, that sort of thing. It`s a tricky job to get done, but they have something that might help them out that`s really unique to a race circumstance like this: every single runner on this course had to wear an electronic tracking tag, that`s how race officials keep track of who`s coming down the course. Now, the runners may not be able to tell them anything, because they were focused on running. But the runners would know where family and friends had gathered along side, to watch their progress.

So, if investigators say, look, we have a witness here who says they saw a man with something, and we have one down here who says, they saw - that they think is the same man, this would allow investigators to go through the runners, through the race organization and say, where were your family and friends? Where they in the middle here? Did they see this person pass by? Something that they may not think much of it, now, may really matter. Normally, investigators would have to wait for those people to come forward. In this case, they have a way to reach out to them, and that could prove very important.

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AZUZ: There`s a quote from the late children`s TV star Mr. Rogers that we mentioned in yesterday`s show. Talks about in times of disaster looking for the helpers. And there were plenty of those in Boston on Monday.

After the bombs went off, first responders ran toward the site of the blast. Police, paramedics, other emergency personnel. And other people, ordinary citizens, also jumped in to help.

One of them was Carlos Arredondo, he was at the marathon to honor his two sons, one of whom died while serving in Iraq. Arredondo said he`s a member of the Red Cross and has some emergency training. He came to the aid of a man with severed leg wounds and stayed with him until paramedics arrived.

Dr. Natalie Stavas, a pediatrician was running the marathon with her dad. They were almost at the finish line, when the explosions happened. Anderson Cooper asked her about what she saw she made her way over to help.

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ANDERSON COOPER, CNN CORRESPONDENT: You`re a doctor, you`re obviously trained to see blood, to see casualties and death.

DR. NATALIE STAVAS: It was horrific. It was - it was the worst thing I have ever seen.

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AZUZ: Dr. Stavas moved through the crowd, giving medical aid to several victims of the bombing. Other people found ways to help away from the blast side. Joe Andruzzi, a former player with the New England Patriots, saw an injured woman being carried by what looked like a teenager. He ran to help, carrying the wounded woman to safety. Another runner, Julia Jeski (ph) finished the race ten minutes before the bombs went off. She offered her cell phone to a stranger who was trying to find her husband.

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UNIDENTIFIED FEMALE: I gave her a hug and I said, I just know your family is going to be fine.

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AZUZ: Medical aid, physical support, emotional comfort - people finding all sorts of ways to help others. If you`re looking for a way to get involved, go to the resources box on our home page and look for the Impact Your World link.

Our next story today involves something called ricin, it`s one of the most dangerous types of poison on earth. There is no specific test for exposure, and there is no cure for ricin poisoning. You`re not going to get exposed to this stuff on accident. But it has been used as a weapon.

On Tuesday, two letters, one to a senator and one to the president, were intercepted. Initial tests show they had ricin in them. The letters never made it to the Senate or the White House. A processing center that screens mail sent to the U.S. government, got hold of them.

Now, here you can see some people who deal with hazardous materials getting ready to investigate. After this happen, reports of other suspicious packages and envelopes came in from two Senate office buildings. Police are investigating those, the FBI says it has no evidence that the ricin scare is tied to the Boston terrorist bombings.

There was a significant vote yesterday in the U.S. Senate. It didn`t approve an expansion of background checks for gun sales in the U.S. The president has been pushing for new laws following last year`s school shooting in Newtown, Connecticut. This would have been part of a package of them. But since it didn`t pass the Senate, it`s seen as a defeat for people who want new gun laws and a victory for those who don`t want them.

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UNIDENTIFIED FEMALE: Today`s "Shoutout" goes out to Mr. Mannino`s U.S. government and world history classes at Foothill High School in Henderson, Nevada.

What is an epigram? You know what to do here. Is it a type of poem, font, novel or hairstyle? You`ve got three seconds, go!

And epigram is a poem that`s usually short, witty and deals with a single subject.

That`s your answer and that`s your "Shoutout."

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AZUZ: Well, April is national poetry month, and to honor the event, we are looking at some famous poets and their famous words, and we`re doing it like a quiz.

First, what poet wrote, "Two roads diverged in a wood, and I, I took the one less traveled by, and that has made all the difference."

The answer - Robert Frost wrote that in his poem, "The Road Not Taken".

Next, what bird quotes "Nevermore" in an Edgar Allan Poe poem? We referenced this one in our show a couple of months back. That bird would be the raven, tapping, tapping at your chamber door?

Finally, which poet asked, "What happens to a dream deferred? Does it dry up like a raisin in the sun?" The answer here, Harlem Renaissance poet Langston Hughes wrote those words.

If you score perfectly on our quiz, you might be a poetry wiz. Perhaps, you can pose your own verse in language that`s flowing or terse, regardless, we hope you`ll take time in this month to commemorate rhyme.

All right. The guys featured in our last report today grew up watching robots and science fiction movies. He assumed they`d be a regular part of his life as an adult, but since that hasn`t happened, he took matters into his own hands, and he might be able to put robots in yours. Watch this.

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KELLER RINAUDO, CEO/FOUNDER, ROMOTIVE: This is Romo. He is a Smartphone robot, so he uses your iPhone or iPod touches his brain. He`s a WiFi enabled, computer vision capable robot. So he can do a lot of really cool things, he can follow your face and recognize different people. You can program him through the browser, so you can actually create your own unique behaviors for the robot.

I think he`s kind of bored. He is like, let`s fly. You can also control him from (inaudible) device locally or you can control him through the browser from anywhere in the world. So, if you have a robot at home, you can invite your grandma or your parents, or a friend to control him through the browser, and their face appears on Romo. It streams two-way audio and video. It`s kind of like Skype on wheels.

If you have a young kid, that kid can send an invitation to grandma and grandma can log in and play, honey, go seek with her granddaughter for 15 minutes every single night. Or otherwise, she might only get to see her once or twice a year.

Research has already indicated that robots can be really effective at helping autistic kids learn how to empathize in social situations. But those robots tend to be incredibly expensive. Romo is a natural way of making that kind of technology available to autistic kids all over the country.

We feel really strongly that the future of personal robotics is personal. And so, we really want to create a robot that normal people - without coding experience can - can program and that they can create unique behaviors and personalities for that robot and then share them.

In our opinion, some of the things that people build for Romo are going to make him very useful in the same way that a lot of geeks were building things for personal computers that turned out to be very useful.

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AZUZ: He`s obviously put a lot of thought into this, even if it seems like he`s kind of phoning it in. It`s time for us to grow, but teachers, don`t forget to share your feedback about today show. The link is up on our home page. We`ll be back tomorrow with more CNN STUDENT NEWS.